1. Field of the Invention
The present invention relates to a global positioning system (hereinafter, referred to as "GPS") receiver, and in particular relates to a GPS receiver having improved operability.
2. Description of the Background Art
In GPS receivers, position data of a destination is preset, and three dimensional position data of an operator's current position is obtained from radio waves emitted from GPS satellites Orbiting the earth. On the basis of these position data, information concerning the distance to the destination and direction with respect to the destination or the like is obtained, and then thus-obtained information is displayed for guiding or navigating the operator to the destination according to the displayed information. Among these GPS receivers as described above, there are portable GPS receivers. Such portable GPS receivers are used for a wide range of activities, examples of which include marine sports such as yachting and fishing, outdoor sports such as mountain climbing and mountain biking, and sky sports such as hang-gliding and hot air ballooning.
Now, when a GPS receiver is used for the activities mentioned above, the GPS receiver must use different units or formats for representing distances and directions appropriately for each of such activities. Namely, when a GPS receiver is used for driving or touring, distance should be indicated in kilometers (or miles) and direction should be indicated with respect to the north, south, east and west directions, but when the GPS receiver is used for marine sports, distance should be indicated in nautical miles and direction should be indicated in degrees. Furthermore, when the GPS receiver is used on the sea for marine sports, it is unnecessary for the GPS receiver to display data representing height or altitude. Further, in this case, coordinates for specifying a position only need an accuracy in units of minutes, while land use requires an accuracy in units of seconds.
With the conventional GPS receivers, an operator must previously set operating condition by setting the units and format for representing distance and direction so as to meet with expected use, and then the GPS receiver displays distance and direction according to the thus-set operating condition. For this reason, each time when the using conditions for the GPS receiver change during use, the units and format for the GPS receiver need to be changed in each change of the using conditions. For example, when an operator reaches a seaside by vehicle such as automobile, cruises by boat, and then travels by automobile again, the units and format for the GPS receiver need to be changed in each travel. However, with the conventional GPS receivers, only one operating condition setting for one operation mode is possible, and for this reason an effective display is possible only for the actual using condition that matches such operation mode of the GPS receiver. Accordingly, it is necessary to reset the operating condition of the conventional GPS receivers each time when the using conditions change.
Furthermore, operation of the conventional GPS receivers is a very time-consuming process because each parameter of the operating condition must be changed or confirmed manually one at a time. Moreover, as the operations required to set the parameters of the operating condition of such GPS receivers are extremely complex, mistakes are likely to be caused while setting the operating condition.